Modeling Guide
Knowledge Guides /How do you model system interfaces? From port definitions to interface control documents
Last updated: · New Horizon Digital Outsourcing Team
Interface modeling should first clarify what the two sides exchange, when they exchange it, and how errors are handled, before choosing a graphical representation. Data fields, physical quantities, and timing constraints must be inspectable. Interface control documents should be generated from the model baseline or have an explicit version mapping to it.
An interface inventory is more than an equipment connection diagram
- Each connection should identify its provider, consumer, and boundary. Record the necessary properties separately for power, mechanical mounting, heat exchange, and message interfaces; one untyped arrow cannot represent every interaction. Examine cross-organization or cross-supplier boundaries first, as these interfaces generally need clearer responsibilities and confirmation mechanisms.
Agree on normal and exception flows together
- Message interfaces must specify field types, units, timestamps, valid ranges, and exceptional values, as well as handling of timeouts, retries, and duplicate messages. Mechanical interfaces need datums, coordinates, and allowable tolerances. Constraints lacking documentation remain pending confirmation; they must not be assumed from experience with common equipment.
How to coordinate with software and simulation
- Create input/output examples from a representative interface and map them to software protocols or simulation variables. Specifically check identically named variables with different units, changes in enumeration meanings, and coordinate directions. Models and code are not automatically synchronized; updating either side should trigger a difference check and confirmation by the responsible person.
What evidence should acceptance examine?
- Deliver a port dictionary, interface control tables, version records, and integration examples. Reviews should verify more than whether the two ends are connected: both sender and receiver should explain message semantics and demonstrate timeout and invalid-input handling. Cross-team interfaces should have a baseline accepted by both parties.